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Dr Themis Prodromakis

University of Southampton
Nano Group, Southampton Nanofabrication Centre
Southampton, SO17 1BJ, UK
+44 (0)23 8059 8803


Coexistence of Memory-Resistance and Memory-Capacitance in TiO2 Solid State Devices

Iulia Salaoru, Qingjiang Li , Ali Khiat, Themistoklis Prodromakis

This work exploits the coexistence of both resistance and capacitance memory effects in TiO2 based two terminal cells.

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Stochastic switching of TiO2-based memristive with identical initial memory states

Qingjiang Li, Ali Khiat, Iulia Salaoru, Hui Xu and Themistoklis Prodromakis

In this work, we show that identical TiO2-based memristive devices that possess the same initial resistive states are only phenomenologically similar as their internal structures may vary significantly, which could render quite dissimilar switching dynamics.

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Memory Impedance in TiO2 based Metal-Insulator-Metal Devices

Qingjiang Li, Ali Khiat, Iulia Salaoru, Christos Papavassiliou, and Themistoklis Prodromakis

Here we demonstrate that TiO2-based metal-insulator-metal devices are more than just a memory-resistor. They possess resistive, capacitive and inductive components that can concurrently be programmed; essentially exhibiting a convolution of memristive, memcapacitive and meminductive effects.

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A versatile, low-cost platform for testing large ReRAM cross-bar arrays

Serb, A., Berdan, R., Khiat, A., Papavassiliou, C. and Prodromakis, T.

We demonstrate a testing platform that allows the manipulation of memristor cross-bar arrays by use of little more than a computer with MATLAB, an mBED and some external components mounted on a PCB.

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Origin of stochastic resistive switching in devices with phenomenologically identical initial states

Qingjiang, Li, Khiat, A., Salaoru, I., Hui, X. and Prodromakis, T.

Here we demonstrate the relation between pristine resistive states and distribution of filaments via modeling the switching dynamics by utilizing a current percolation circuit. We show that devices with identical initial resistive states could attain distinct plausible filamentary distributions and correspondingly manifest very dissimilar switching dynamics even when biased with similar stimuli.

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Qualitative SPICE modeling accounting for volatile dynamics of TiO2 memristors

Berdan, R., Khiat, A., Papavassiliou, C. and Prodromakis, T.

We propose a SPICE model that describes qualitatively real memristor device operation. Namely we introduce volatile effects, rate-dependent resistive switching and unipolar effects which can be tailored to influence together or separately the device's resistance.

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Memristors as synapse emulators in the context of event-based computation

Serb, A., Berdan, R., Khiat, A., Shari, L., Vasilaki, E., Papavassiliou, C. and Prodromakis, T.

This paper examines the widespread Biolek and Pershin models of the memristor in order to find out whether they support STDP in an event-based computation environment.

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Applications of solid-state memristors in tunable filters

Wizenberg, R., Khiat, A., Berdan, R., Papavassiliou, C. and Prodromakis, T.

In this paper we present a practical approach to employ solid-state TiO2 memristors as tunable loads in filter configurations. First, memristive devices are employed in discrete realizations of tunable active filter topologies.

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Origin of the OFF state variability in ReRAM cells

Salaoru, I., Khiat, A., Berdan, R., Quingjian, L., Papavassiliou, C. and Prodromakis, T.

This work exploits the switching dynamics of nanoscale Resistive Random Access Memory (ReRAM) cells with particular emphasis on the origin of the observed variability when consecutively cycled/programmed at distinct memory states.

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Resistive switching characteristics of indium-tin-oxide thin film devices

Ali Khiat, Iulia Salaoru, and Themistoklis Prodromakis.

We demonstrate that indium–tin-oxide (ITO), when used as an active core material in metal–insulator–metal type devices, facilitates resistive switching.

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A Memristor SPICE Model Accounting for Volatile Characteristics of Practical ReRAM

Radu Berdan, Chuan Lim, Ali Khiat, Christos Papavassiliou and Themistoklis Prodromakis

Realizing large-scale circuits utilizing emerging nanoionic devices known as memristors depends on the accurate modeling of their behavior under a wide range of biasing conditions.

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Pulse-induced resistive and capacitive switching in TiO2 thin film devices

Iulia Salaoru, Ali Khiat, Qingjiang Li, Radu Berdan, and Themistoklis Prodromakis

In this study, we exploit the non-zero crossing current–voltage characteristics exhibited by nanoscale TiO2 based solid-state memristors.

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Pulse-induced resistive and capacitive switching in TiO2 ReRAM

Iulia Salaoru, Ali Khiat, Radu Berdan and Themistoklis Prodromakis

In this study, we provide the experimental evidence of the coexistence of resistive and capacitive features in nanoscale TiO2 based solid state Resistive Random Access Memory (ReRAM).

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Memristors: Two Centuries On

T. Prodromakis, C. Toumazou and L.O. Chua

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Temporal processing with volatile memristors

F. Perez-Diaz, E. Vasilaki, R. Berdan, A. Khiat, I. Salarou, C. Toumazou and T. Prodomakis

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Temporal Processing with Volatile Memristors

R. Berdan, T. Prodromakis, F.P. Diaz, E. Vasilaki, A. Khiat, I. Salaoru and C. Toumazou

We studied the memory mechanisms in emerging non-CMOS devices with a view to application in temporal pattern recognition and detection, inspired by the STP mechanisms.

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“Biomimetics - Products”, Encyclopedia of Nanotechnology

B. Bhushan and T. Prodromakis

Biomimetics - Products

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A. Gelencser, T. Prodromakis, C. Toumazou and T. Roska, “A Biomimetic Model of the Outer Plexiform Layer by Incorporating Memristive Devices

A. Gelencser, T. Prodromakis, C. Toumazou and T. Roska

In this paper we present a biorealistic model for the first part of the early vision processing by incorporating memristive nanodevices.

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Integration of nanoscale memristor synapses in neuromorphic computing architectures

G. Indiveri, B. Linares-Barranco, R. Legenstein, G. Deligeorgis and T. Prodromakis

In this paper, we propose a novel hybrid memristor-CMOS neuromorphic circuit which represents a radical departure from conventional neuro-computing approaches, as it uses memristors to directly emulate the biophysics and temporal dynamics of real synapses.

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Computing Motion with 3D Memristive Grid

C.K.K. Lim and T. Prodromakis.

Here, we introduce a novel memristive thresholding scheme that facilitates the detection of moving edges.

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Computing shortest paths in 2D and 3D memristive networks

Z. Ye, M. Wu-Shihong and T. Prodromakis

In this paper we show how networks of memristive elements can be utilised to solve multiple shortest paths in a single network.

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Memristive Devices as Parameter Setting Elements in Programmable Gain Amplifiers

R. Berdan, T. Prodromakis, I. Salaoru, A. Khiat and C. Toumazou

In this paper, we investigate the AC performance of a variable gain amplifier that utilizes an in-house manufactured memristor as a gain setting element.

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Resistive switching of oxygen enhanced TiO2 thin-film devices

I. Salaoru, T. Prodromakis, A. Khiat and C. Toumazou

In this work, we investigate the effect of oxygen-enhanced TiO2 thin films on the switching dynamics of Pt/TiO2/Pt memristive nanodevices.

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A Proposal for Hybrid Memristor-CMOS Spiking Neuromorphic Learning Systems

T Serrano-Gotarredona, T. Prodromakis, B Linares-Barranco

Here we propose a hybrid memristor-CMOS system architecture with the potential of implementing a large scale STDP learning spiking neural system.

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Homeostatic plasticity in Bayesian spiking networks as Expectation Maximization with posterior constraints

S. Habenschuss, J. Bill, B. Nessler

This paper investigates how homeostatic intrinsic plasticity (that arguably can be implemented in neuromorphic hardware) facilitates synaptic learning in Bayesian spiking network models and renders circuit dynamics more robust against distortions and variability in individual units (e.g. mismatches in analog hardware). In particular, the examined intrinsic plasticity rule is compatible with the winner-take-all architectures employed in the PNEUMA project.

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A 128x128 1.5% Contrast Sensitivity 0.9% FPN 3us Latency 4mW Asynchronous Frame-Free Dynamic Vision Sensor Using Transimpedance Amplifiers

T. Serrano-Gotarredona and B. Linares-Barranco

Silicon Retina modeling the magno-cellular retina-brain pathway.

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STDP and STDP Variations with Memristors for Spiking Neuromorphic Learning Systems

T. Serrano-Gotarredona, T. Masquelier, T. Prodromakis, G. Indiveri, and B. Linares-Barranco

Implemetation of STDP with memristors.

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Multi-Casting Mesh AER: A Scalable Assembly Approach for Reconfigurable Neuromorphic Structured AER Systems. Application to ConvNets

C. Zamarreño-Ramos, A. Linares-Barranco, T. Serrano-Gotarredona, and B. Linares-Barranco

Routing techniques for multi-chip spiking systems.

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A 0.35um Sub-ns Wake-up Time ON-OFF Switchable LVDS Driver-Receiver Chip I/O Pad Pair for Rate-Dependent Power Saving in AER Bit-Serial Links

C. Zamarreño-Ramos, T. Serrano-Gotarredona, and B. Linares-Barranco

Driver circuits for inter-chip bit-serial high-speed communications

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Comparison between frame-constrained fix-pixel-value and frame-free spiking-dynamic-pixel convNets for visual processing

C. Farabet, R. Paz, J. Pérez-Carrasco, C. Zamarreño-Ramos, A. Linares-Barranco, Y. LeCun, E. Culurciello, T. Serrano-Gotarredona, and B. Linares-Barranco

Comparison of frame-based vision versus event-based vision

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On spike-timing-dependent-plasticity, memristive devices, and building a self-learning visual cortex

C. Zamarreño-Ramos, L. A. Camuñas-Mesa, Jose A. Perez-Carrasco, T. Masquelier, T. Serrano-Gotarredona, and B. Linares-Barranco

Implementation of STDP with memristors

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Two Centuries of Memristors


Memristors are dynamic electronic devices whose nanoscale realization has led to considerable research interest. However, their experimental history goes back two centuries.

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A Versatile Memristor Model With Non-linear Dopant Kinetics


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Biomimetic Model of the Outer Plexiform Layer by Incorporating Memristive Devices


A biomimetic application of nanoscale memristors.

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High precision analogue memristor state tuning


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Concurrent Resistive and Capacitive Switching of Nanoscale TiO2 Memristors


This paper provides experimental evidence on a switching mechanism that depends upon the expansion/contraction of a TiO2 thin film that serves as the active core for a nanoscale memristor, due to a re-oxidation/de-oxidation (reduction of TiO2) process supported at the top TiO2/Pt interface of the device.

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Funding Research Councils:
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